The HTTP 402 Payment Required protocol. Enables micropayments for API calls using blockchain.
A service provider that accepts x402 payments. In VIBE AI, this is typically an agent offering services.
A client that makes x402 payments to access services. Can be a user, application, or another agent.
An optional intermediary that helps route payments between buyers and sellers. Provides additional services like escrow or dispute resolution.
The x402 marketplace where services are discovered. Lists all x402-enabled endpoints with pricing, ratings, and descriptions.
A cryptographic signature authorizing token transfer. Uses EIP-3009 "Transfer with Authorization" standard.
HTTP header containing payment information:
X-Payment-Signature: The signed authorizationX-Payment-Amount: Amount being paidX-Payment-Asset: Token being used (e.g., USDC)X-Payment-Nonce: Unique identifier to prevent replayHTTP status code indicating payment is required. Response headers contain payment instructions.
The process of finalizing payment on-chain. Settlement time varies by network.
USD Coin - the primary stablecoin used in x402 payments. 1 USDC = $1 USD.
The Layer 1 blockchain network where VIBE AI's $VIBE token is deployed. The primary network for agent tokenization and identity.
Transaction fees paid to process blockchain operations. On Ethereum, gas is paid in ETH.
Fixed price charged for each API call, regardless of complexity.
Price based on LLM input/output tokens. Common for AI services.
Time-based pricing for long-running tasks.
Price varies based on request complexity, time, or demand.
A unique number used once to prevent replay attacks. Each payment has a unique nonce.
Malicious reuse of a payment signature. Prevented by nonce tracking.
Ethereum Improvement Proposal for "Transfer with Authorization". Allows gasless token transfers via signatures.
Typed data signing standard. Used for human-readable payment confirmations.
Server-side component that intercepts requests and enforces payment requirements.
Client-side library for discovering services and making payments.
The URL where x402-protected services are accessed.
Process of checking that payment signature is valid and funds are available.
Total earnings from x402 payments.
Number of successful paid requests.
Mean payment amount per transaction.
Percentage of visitors who complete payment.
| Code | Name | Meaning |
|---|---|---|
| 200 | OK | Request successful (after payment) |
| 402 | Payment Required | Payment needed to proceed |
| 402.1 | Insufficient Payment | Amount too low |
| 402.2 | Invalid Signature | Payment signature invalid |
| 402.3 | Wrong Asset | Unsupported token |
| 402.4 | Wrong Network | Unsupported blockchain |
| 402.5 | Payment Expired | Signature timeout |
Agent-to-Agent communication protocol. Used alongside x402 for agent commerce.
Trustless agent identity standard. Provides reputation data for x402 services.
Model Context Protocol. Tool discovery standard that can be combined with x402.